The compound 1,1,1,3,3-pentachloropropane (HCC-240fa) is a raw material for producing 1,1,1,3,3-pentafluoropropane (HFC-245fa), which is a non-ozone depleting chemical and can be used as blowing agent, energy transfer medium, and so on. Addition reactions for preparing useful haloalkanes, such as HCC-240fa, are known in the art. For example, U.S. Pat. No. 6,313,360 teaches a process for producing HCC-240fa by reacting carbon tetrachloride (CCl4) and vinyl chloride (VCM) in the presence of a catalyst mixture comprising organophosphate, e.g., tributyl phosphate (TBP), metallic iron and ferric chloride under conditions sufficient to produce a product mixture containing HCC-240fa. The 240fa product is then recovered by separating it from reactants, catalyst and by-products. See also, U.S. Pat. Nos. 5,902,914, 6,187,978, 6,198,010, 6,235,951, 6,500,993, 6,720,466, 7,102,041, 7,112,709 and 7,265,082 and U.S. Patent Publication Nos. 2004/0225166 and 2008/0091053. The disclosures of all of these references are hereby incorporated herein by reference.
Iron powder is used as the primary catalyst during the synthesis of HCC-240fa via the coupling reaction between CCl4 and VCM. The liquid medium, consisting of CCl4, TBP, and 240fa, forms a slurry with the iron powder. As such, the reactor effluent will contain a substantial quantity of suspended solids which could potentially upset the mechanical and chemical operations of downstream units. Furthermore, as catalyst is removed from the effluent, the reactivity will suffer, increasing the required make-up of lost iron powder. Hence, there is a need for means by which iron catalyst can be captured and recycled back to reactor. The present invention provides a solution to this problem.